Among electronic devices using a secondary battery, there are electronic devices including a function of detecting the remaining battery capacity. In order to detect the remaining capacity of a secondary battery, it is necessary to detect the terminal voltage in a no-load condition (such a voltage is called “OCV (Open Circuit Voltage)”). Patent Document 1 describes a calculation method for obtaining the remaining capacity of a secondary battery. In the secondary battery remaining capacity calculation method described in Patent Document 1, when the relative remaining capacity SOC of a secondary battery is to be obtained from the open circuit voltage OCV of the secondary battery with reference to a table which shows previously obtained relationships between the open circuit voltage of the secondary battery and the relative remaining capacity [%], an open circuit voltage OCVfull in the full-charge condition of the secondary battery is detected, a relative remaining capacity SOCfull [%] is obtained with reference to the table in accordance with the open circuit voltage OCVfull, and the relative remaining capacity SOC which is obtained with reference to the table in accordance with the open circuit voltage OCV of the secondary battery that is detected when the discharge of the secondary battery is stopped is then corrected by SOCtrue=SOC×(100/SOCfull) based on the relative remaining capacity SOCfull [%] in the full-charge condition, thereby obtaining the true relative remaining capacity SOCtrue of the secondary battery.